CN108135296B

CN108135296B - System and method for thermally adaptive materials

Info

Publication number: CN108135296B
Application number: CN201680042705.7A
Authority: CN
Inventors: B.里利; S.格里菲思; S.麦克兰斯; J.常; P.林
Original assignee: Autotel Laboratories LLC
Current assignee: Autotel Laboratories LLC
Priority date: 2015-05-21
Filing date: 2016-05-20
Publication date: 2021-01-12
Anticipated expiration: 2036-05-20
Also published as: KR102409006B1; EP3297471A4; US10793981B2; US11686024B2; KR20180022689A; EP3297471A1; CA2986043A1; US20230357970A1; US20210025091A1; CN108135296A; JP7020919B2; JP2018522144A; WO2016187547A1; US20160340814A1

Abstract

An adaptive sheet comprising a first layer defining a first length, the first layer configured to assume a base configuration responsive to a first environmental condition and assume a lofted configuration responsive to a second environmental condition, wherein the first layer curls along the first length as compared to the base configuration. The first fabric layer comprises: a first material defining a second length and having a first coefficient of expansion, and wherein the first material is configured to gradually change in length along the second length in response to a second environmental condition; and a second material defining a third length and having a second coefficient of expansion different from the first coefficient of expansion.

Description

System and method for thermally adaptive materials

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a non-provisional application No. 62/164,740, filed on day 21, 5/2015, entitled system and METHOD FOR thermally adaptive materials (SYSTEM AND METHOD FOR THERMALLY ADAPTIVE MATERIALS), which is incorporated herein by reference in its entirety and FOR all purposes, and claims priority thereto. This application is also a non-provisional application No. 62/257,126, filed on year 2015, 11/18, entitled system and METHOD FOR thermally adaptive materials (SYSTEM AND METHOD FOR THERMALLY ADAPTIVE MATERIALS), which is incorporated herein by reference in its entirety and FOR all purposes, and claims priority thereto.

Statement regarding federally sponsored research

The invention was made with government support in accordance with DE-AR0000536 awarded by the U.S. department of energy. The government has certain rights in this invention.

Background

The insulation material is conventionally static, while its insulation value is substantially unresponsive to changes in environmental conditions. In view of the foregoing, there is a need for improved adaptive material systems and methods to address the aforementioned obstacles and deficiencies of conventional insulation materials.

Disclosure of Invention

One aspect includes a thermally adaptive garment having a garment body defined by a thermally adaptive fabric configured for wearing on a user and surrounding the user's body, the fabric comprising an interior face configured to face the body of the wearing user; an exterior face configured to face an environment exterior to a wearing user; a first fabric layer defining at least a portion of an exterior face; a second fabric layer defining at least a portion of the interior face and coupled to the first fabric layer at one or more seams; and a plurality of cavities defined by and disposed within the first and second fabric layers and the one or more seams.

In one embodiment, the first fabric layer is configured to assume a base configuration responsive to a first ambient temperature range, wherein the first fabric layer is spaced from the second fabric layer by a first average distance; and the first fabric layer is configured to assume a lofted configuration responsive to a second ambient temperature range different from the first ambient temperature range, wherein the first fabric layer is spaced from the second fabric layer by a second average distance greater than the first average distance.

In another embodiment, when the ambient temperature increases from the first ambient temperature range, the average distance between the first and second layers increases in response to a temperature within the second temperature range. In another embodiment, the garment body mechanically defines a third ambient temperature range adjacent to the second ambient temperature range and different from the first ambient temperature range, wherein the increased average distance between the first and second layers is limited to a maximum distance by the physical configuration of the garment body. In yet another embodiment, the temperature of the second ambient temperature range is less than the temperature of the first ambient temperature range.

In one embodiment, the first fabric layer comprises a first material defining a first length, and wherein the first material is configured to gradually expand along the first length in response to a temperature change within a second ambient temperature range according to a first coefficient of thermal expansion.

In another embodiment, the first fabric layer comprises a second material defining a second length parallel to the first length, and wherein the second material is configured to gradually expand along the second length in response to temperature changes within a second ambient temperature range according to a second coefficient of thermal expansion that is different from the first coefficient of thermal expansion.

In another embodiment, the first and second materials are substantially planar and coupled together along the coupling face. In yet another embodiment, the first and second materials define respective first and second widths perpendicular to the first and second lengths, and wherein the first and second widths remain substantially unchanged in response to temperature changes within the second ambient temperature range.

Another aspect includes a thermally adaptive fabric comprising a fabric layer defining a first length, the fabric layer configured to assume a flat base configuration responsive to a first temperature range and assume a lofted configuration responsive to a second temperature range, wherein the fabric layer curls along the first length as compared to the base configuration. The fabric layer may include: a first material defining a second length and having a first coefficient of thermal expansion, and wherein the first material is configured to gradually change length along the second length in response to temperature changes within a second ambient temperature range; and a second material defining a third length and having a second coefficient of thermal expansion different from the first coefficient of thermal expansion.

In one embodiment, the first material includes at least one coiled actuator comprising alternating achiral and homochiral portions configured to respond in opposite ways to temperature changes, respectively. In another embodiment, the first fabric layer is configured to exhibit an area change of no more than 5% in response to a temperature change of 10 ℃. In another embodiment, the first and second materials define a plurality of interwoven and corresponding first and second fibers. In yet another embodiment, the first material comprises a thermally adaptive coil configured to contract or expand along a first length. In yet another embodiment, the first material comprises a flat sheet.

Another aspect includes an adaptive sheet that includes a layer defining a first length, the first layer configured to assume a base configuration responsive to a first environmental condition and assume a lofted configuration responsive to a second environmental condition, wherein the first layer curls along the first length as compared to the base configuration. The first layer may include: a first material defining a second length and having a first coefficient of expansion, and wherein the first material is configured to change length along the second length in response to a second environmental condition; and a second material defining a third length and having a second coefficient of expansion different from the first coefficient of expansion.

In one embodiment, the first environmental condition comprises a first temperature range and the second environmental condition comprises a second temperature range different from the first temperature range and comprising a temperature less than the first temperature range. In another embodiment, the first environmental condition comprises a first humidity range and the second environmental condition comprises a second humidity range different from the first humidity range.

In another embodiment, the first fabric layer comprises a first plurality of wires arranged in at least a first direction and the second fabric layer comprises a second plurality of wires arranged in at least a second direction that is not parallel to the first direction, and wherein the first and second plurality of wires are configured to be coupled in the base configuration to form a wire mesh having infrared reflectance and absorbance characteristics that are different from the reflectance and absorbance characteristics of the first and second plurality of wires in the spaced configuration.

In yet another embodiment, the first and second adaptive materials define a portion of the braid. In yet another embodiment, the first and second adaptive materials define a portion of the knit.

Drawings

Fig. 1a is a diagram of an exemplary bimorph comprising first and second materials at a flat temperature, wherein the bimorph is flat and unbent.

Figure 1b shows the bimorph of figure 1a at different temperatures and in a curved configuration.

Fig. 2a is an illustration of an exemplary bimorph having an alternating structure comprising first and second materials, wherein the first materials are shown in an alternating pattern on opposite sides of the second material and coupled at respective coupling interfaces.

Figure 2b shows the bimorph of figure 2a at different temperatures and in a curved configuration.

Figure 3 shows an exemplary bimorph structure in a lofted state comprising first and second bimorphs.

Figure 4a shows an exemplary bimorph structure configured to bend along two axes.

Figure 4b shows the bimorph of figure 4a at different temperatures and in a curved configuration.

Fig. 5a and 5b illustrate examples of how the bimorph of fig. 1a and 1b can be used in multiple as loose thermally adaptive fillers and the like.

Figure 6a shows an exemplary helical bimorph structure at a flat temperature.

Figure 6b shows the bimorph structure of figure 6a undergoing displacement in response to a change in temperature.

Figure 7 shows a top or plan view of a structure comprising four exemplary dual-layer bimorphs interconnected in a repeating patch or unit cell form that can be used to fabricate a bimorph sheet.

Figure 8a illustrates an open configuration of a bimorph structure, wherein the bimorphs form cavities separating corresponding lines on the upper and lower bimorphs.

Figure 8b illustrates the closed configuration of the bimorph structure of figure 8a, wherein the bimorphs are in contact with horizontal and vertical lines that are in contact or in close proximity.

Figure 9a illustrates one exemplary apparatus and method for fabricating a bimorph.

Figure 9b illustrates a close-up perspective view of the edge of the bimorph of figure 9a produced by the apparatus of figure 9 a.

Figure 10 shows an embodiment of a roller having a corrugated surface pattern configured to produce the flat bimorph structure shown in figure 11.

Fig. 12a and 12b illustrate an exemplary bimorph comprising a coiled actuator and a filament coupled at first and second ends.

Figure 13a illustrates an exemplary embodiment of a bimorph with a wound actuator and a filament, wherein the wound actuator maintains a linear configuration when the bimorph is in a flat configuration (left) and a curved configuration (right).

Figure 13b illustrates a bimorph comprising first and second filaments, and a coiled actuator between the first and second filaments.

Fig. 14a illustrates an exemplary embodiment in which the coiled actuators have opposite thermal responses and remain contiguous in the flat configuration (left) and the curved configuration (right).

Fig. 14b illustrates an exemplary embodiment in which the wrap actuators are contiguous in a flat configuration (left) and separable in a curved configuration (right).

Figure 15 illustrates an exemplary embodiment of a bimorph with a wound actuator and a filament, wherein the filament maintains a linear configuration when the bimorph is in a flat configuration (left) and a curved configuration (right).

Fig. 16 illustrates a dual mandrel structure for manufacturing a wound actuator having alternating regions of heterochirality and homochirality that can respond in opposite ways to changes in temperature.

Fig. 17 illustrates one exemplary embodiment of a thermally adaptive braided structure.

Fig. 18a and 18b illustrate a thermally responsive woven structure in a bag or quilted that shows lofting in response to an increase in temperature.

Fig. 19a and 19b illustrate a thermally responsive braided structure, which shows lofting in response to a decrease in temperature.

It should be noted that throughout the drawings, the drawings are not necessarily drawn to scale and elements of similar structure or function are generally represented by the same reference numerals for illustrative purposes. It should also be noted that the figures are only intended to facilitate the description of the preferred embodiments. The drawings are not intended to illustrate every aspect of the described embodiments and are not intended to limit the scope of the invention.

Detailed Description

For a variety of applications, a garment, blanket or textile comprising an insulating material (a material responsive to temperature changes) with variable thermal insulation may be desired. In addition to improved human thermal comfort, such materials can achieve significant energy savings, as over 10% of the energy translates into heating and cooling of buildings, and heating and cooling costs can be reduced through widespread use of thermally adaptive materials.

In various embodiments, the thermally adaptive material may be a material that changes its insulative value in response to changes in temperature. Such thermal actuation can be achieved by using bimorphs, or alternatively, materials that undergo a phase change at a target temperature, including (but not limited to) shape memory polymers and materials that undergo glass transition. In some embodiments, it may be desirable for the bimorph to continuously react to temperature changes, bending or straightening as the temperature changes.

In contrast, some materials respond in a stepwise manner to temperature with a phase change occurring at a single temperature. Such materials may be used according to various embodiments to achieve a continuous response characteristic by using a set of materials with different phase transition temperatures.

Bimorphs can comprise two or more materials laminated, glued, welded, or otherwise connected, bonded, or constrained together in any suitable manner. In some embodiments, the bimorphs can have different thermal expansion characteristics such that one side of the bimorph expands more than the other side as the ambient temperature changes, causing the bimorph to bend. A bimorph can have a "flat temperature" (at which the structure is flat). In some embodiments, above and below such "flat temperatures," both bimorphs can bend, in opposite directions, due to the difference in thermal expansion in the two layers.

This temperature controlled bending in the bimorph can be exploited to build fabrics and garments with temperature dependent properties — as the temperature drops, the fabric becomes thicker, thereby becoming more insulating, and/or as the temperature rises, the fabric becomes more sparse, thereby becoming more porous and making it cooler.

To achieve the relatively large variation in thickness that can be expected for a thermally adaptive material, the arrangement of the bimorph fibers, ribbons, or foils can be controlled such that the combined variation across the multiple layers produces the desired variation.

The amount of change in displacement of an individual bimorph can depend on the temperature difference, the difference in the coefficients of thermal expansion of two or more materials in the bimorph, the stiffness of the materials, and the thickness and length of the bimorph. In some embodiments, the difference in thermal expansion coefficients may be small, and for commercial materials, the difference is at most about 100-200 μm/m/K.

For example, a thickness variation of about 1 mm may be targeted for some clothing and bedding applications. Using 10 microns as an exemplary assumed thickness for each of the layers in a bimorph (thickness comparable to a thin fiber) and using a temperature change of 10 kelvin (reasonable range of variation of room temperature), then to achieve a displacement of 1 mm, the fiber length would need to be 10 mm. In some embodiments, it may be desirable for a bimorph undergoing this change to be free to move throughout its length, and any contact with other fibers or surface layers may impair or even completely impede motion. Free fiber motion within such lengths is less likely in many garment embodiments, and some embodiments of bimorphs at this length to thickness ratio may have low structural resistance to external forces. Although this bimorph will produce an effective thickness of 1 mm, when flat, it will be exceptionally thin. This problematic thinness, as well as the problematic large bimorph length, can be addressed by using a multi-layer bimorph structure.

In some embodiments, a thickness change of the thermally responsive material of about 1 mm or more can be achieved by using a multi-layer bimorph structure. In such applications, it may be desirable for the thermally adaptive material to be twice, three times, or even four times its thickness as the ambient temperature decreases to provide increased comfort. Each of the bimorph layers is constructed from a plurality of shorter bimorphs having individually smaller displacements, and each of these bimorph layers can be mechanically coupled within the structure such that the displacement of each layer can contribute to the overall thickness variation of the material. The combination of controlled structures in the bimorph layers and the controlled relationship and structure between the layers can produce a material capable of achieving a desired cumulative thickness change in response to temperature. Additionally, in some embodiments, the multilayer bimorph structure may have improved ability to resist external loads, such as tension or weight of facing fabrics or loads from wind.

One advantage of some embodiments of such multilayer structures may be that larger variations in structure height are possible at only smaller lengths. The shaft may undergo large changes in displacement by having a greater length relative to thickness, but a longer length, free movement may not be desirable for some embodiments of clothing and bedding. Additionally, the force required to resist such motion may become smaller as the length increases. In various embodiments, larger height variations can be achieved only at smaller overall lengths by moving to multiple structured layers each at a smaller length.

In other words, some embodiments of the multilayer structure may have an advantage in that its structure places the individual bimorphs at locations that reinforce and build upon each other, producing large overall thickness variations, when the layers undergo geometric changes in response to temperature changes; some embodiments of the multilayer structure may have a large thickness variation because it is the sum of the small variations of each of the individual bimorph layers. Separately, the individual layers of some embodiments may achieve greater loft variation through material selection, large temperature changes, smaller thickness, or longer length.

In some embodiments, the multilayer thermal actuation structure can be constructed such that most of the physical variation is in one dimension, enabling relatively large variations in thickness while minimizing variations in other dimensions. Bimorphs incorporated into yarns composed of multiple individual fibers twisted together can undergo thickness variations and similar lateral variations. Lateral variations may cause undesirable wrinkling of the overall material and may also require other structural elements in the garment to maintain the desired shape. In various embodiments, the anisotropic nature of the multilayer thermally adaptive structure may address these limitations that may be associated with twisted structures, such as yarns.

In a conventional twisted structure or in a random batt or non-woven structure, the individual fibers, in the case where they are bimorph fibers, may not be held together in a manner that ensures that they move together, in a manner that adds one fiber curve to another to increase the aggregate material thickness. Additional variations may be desired in some embodiments, where each fiber variation works in conjunction with adjacent fibers to produce a large cumulative loft. Twisting, such as those commonly found in yarns, provides the opportunity for the fibers to move or nest together in opposite directions, with one twist moving into the space created by the movement of the other twist. This may result in a yarn or fabric that does not have the full or required thickness variation, which may not be desirable in some embodiments.

Yarns comprising multiple individual fibers may introduce tensile stresses into the fibers twisted together, and such residual stresses may limit the magnitude of the geometric response in some embodiments. Various embodiments of the controlled multilayer structure can be fabricated with minimized stress to allow the bimorph to move more freely and more fully with temperature changes.

Commercial opportunities for thermally adaptive materials exist, for example, in areas where insulation materials are in close proximity to skin and in close association with human thermal comfort, such as clothing, bedding, sleeping bags, and tents. Other application areas may include, but are not limited to, wool fabrics, facing materials, thermal insulation, medicine, filtration, and microfluidics.

In various embodiments, the multilayer structure may comprise a stacked structure including a plurality of fibers or ribbons that undergo thermally conductive flexure. The deflection in such fibers or ribbons may be primarily in one dimension and correspond to the thickness of the garment or felt; when the width of the ribbon is increased or multiple ribbons or fibers run parallel, the overall structure begins to resemble a sheet. In some embodiments, linear expansion may occur substantially along two axes of the overall bimorph structure, resulting in bending and an effective thickness change along the third axis.

The multilayer thermally adaptive structure may be used in adaptive padding, quilting, or inner layers in garments or blankets, where the outer layer may be selected for wear resistance, appearance, and feel, and the inner layer may be selected for feel and wicking properties. The multilayer thermally adaptive structure may be integrated with waterproof, windproof, wicking, or other layers or materials in structures in which other functionality is added by additional layers or lamination or by fibers or yarns that are knitted, woven, or stitched with or through the multilayer structure for specific applications.

In various embodiments, thermally-driven actuation in these structures may be achieved by using bimorph structures, as described in detail below, but may also be achieved by shape memory polymers or other suitable materials that undergo a geometric change in response to a phase change. The individual bimorphs can be constructed by co-extruding, laminating, or depositing one layer onto the other by printing, doctor blading, or other suitable techniques. Where it is desired to pattern one of the layers differently than the underlying layer, the patterned layer may be printed, coated through a mask, etched or deposited as a pre-patterned sheet, or the like, and attached to the other sheet by adhesive, thermal or ultrasonic welding, or some other suitable attachment technique. Where it is desired to pattern the two layers in a similar manner and impart a two-dimensional structure, such as a ribbon or coil, a pre-fabricated bimorph sheet can be given its shape by knife cutting, laser cutting, stamping, etching or similar techniques.

Bimorph structures can also be produced as textile structures, in which two fibers or ribbons with different properties are organized and defined in the following manner: the two materials are placed in adjacent and opposing relation. The textile structure may provide a wide variety of patterns and may be printed on, cut into and typically processed into bimorphs as described above.

There may be a temperature gradient in the insulation. In cold environments, this means that the temperature difference between the thermal insulation layer on the outside of the garment (cooler) and the flat temperature of the layer's bimorph can be substantially greater than the temperature difference between the layer near the skin (warmer) and the flat temperature of the layer's bimorph. The layer closer to the skin may undergo only minor changes while the outer layer may undergo major changes. Due to human thermal regulation, the temperature variation range near the skin may not be as large as the temperature variation range at the garment surface, and the human bimorph layer at the garment surface may experience a larger temperature range than the layer near the skin. In some applications, it may be advantageous to employ different bimorph layers in a multilayer structure, each having a unique flat temperature, such that there is a unique thermal response in the layer close to the body when compared to the thermal response in the layer close to the surface of the temperature sensitive article.

For thermal comfort in garments or blankets, it may be desirable for the thermally adaptive article to assume its minimum lofted state at any temperature above a critical value, with its thickness and insulation values minimized. Simple bimorphs in randomly twisted threads or unstructured pads can be flat at such temperatures, but a decrease or increase in temperature can cause the bimorph to bend and cause an increase in thickness. In some embodiments, this may be undesirable because it means that at high temperatures, the bimorph will undergo geometric changes and will increase the thermal insulation with the same type of characteristics that it has at low temperatures.

In various embodiments, the multilayer thermally adaptive material may address this problem by entering a fully planar state above a critical temperature. This can be designed into a structure where the two bimorphs are mirrored and against each other, producing a flat, minimally bulky structure at all temperatures above a selected value. In some embodiments, a simple bimorph structure can minimize this problem by fabricating the bimorph such that the flat temperature is extremely high and falls outside of the range suitable for clothing. However, this may mean that in some applications the garment may never reach its minimum lofted state, which may be undesirable for some applications.

The following exemplary description focuses primarily on the continuous change of geometry and thermal isolation by bimorphs. However, such structures, as well as those actuated by phase change mechanisms, can also produce bistable systems, and effective thermal insulation changes can be achieved by controlled changes in porosity or optical properties, by geometric manipulation of the grating, optical coating, or optically active material that is sensitive to its dielectric environment or adjacent to adjacent materials, including nanomaterials.

In various embodiments, individual bimorphs or bimorph layers comprise two or more materials joined together. Bimorphs can be fibers, ribbons, foils, or they can be composed of two paired fibers, ribbons, or foils, or in some embodiments they can have more complex geometries or cross-sections. In some embodiments, a bimorph may include two materials with different coefficients of thermal expansion, but may include other materials to improve adhesion between the layers or to adjust some other physical property. In other embodiments, the bimorph may comprise a single material having portions with different coefficients of thermal expansion. In both materials, differences in thermal expansion or other dimensional changes in response to environmental stimuli can cause the bimorph to change shape.

Although various embodiments of bimorphs may include two materials laminated together, in some embodiments, the materials need not be connected or bonded along their entire length, and the pattern or shape between the two materials may differ such that they do not always align with each other. In other embodiments, such a two-layer structure may be present in a textile structure, such as a fabric or knit, where the two fibers or fiber layers in the structure are substantially paired together such that their common properties are similar to those of a laminated bimorph. Like a bimorph, the bilayer structure can be made from a single material in two different forms or with different structures or processing histories such that the two layers have different thermal expansion characteristics, different responses to humidity, or different responses to some other external stimulus.

Additionally, in some embodiments, it may be advantageous to have an alternating or double-sided bimorph structure, wherein a first material or substrate has a second material with a different coefficient of thermal expansion patterned or disposed on both sides of the first material, wherein the pattern alternates, causing the individual bimorphs to bend in an alternating manner in response to temperature changes.

The alternating bimorph structure can have a bending region with local bending and no long-distance bending. The length and thickness of the two materials comprising at least bimorphs can be selected according to the curvature required for a given temperature change and can be controlled to produce regions of varying curvature in the alternating bimorph layers.

The multilayer thermally adaptive material can have a multi-scalar structure that can constrain the bimorph motion so that the displacements of the individual bimorphs add together to produce a large displacement of the multilayer structure. Such constraints can be introduced in simple and/or alternating bimorphs as well as bimorphs having substantially more complex structures. This interlayer order can be introduced by adhesives, welds, adhesives, stitches, etc. between the layers, by a textile structure such as a textile or knitted fabric, or by restrictions imposed by the geometric design of the bimorph structure itself.

The following description of the drawings includes several exemplary embodiments, but should not be construed as limiting the wide variety of other possible embodiments that are within the scope and spirit of the present invention.

Fig. 1a is a diagram of an exemplary bimorph 100A comprising first and

second materials

110, 120 at a flat temperature, wherein the bimorph 100A is flat and unbent. The first material 110 is shown as being defined by a length L1 and a width W1. Second material 120 is shown as being defined by a length L2 and a width W2. In this example, the length L1 of the first material 110 is shorter than the length L2 of the second material 120, and the widths W1, W2 are substantially the same. The first and

second materials

110, 120 can have respective opposing outer surfaces 111, 121 and can be connected together along a coupling plane 115.

Figure 1b shows the bimorph 100 of figure 1a at different temperatures and in a curved configuration. In this example, the temperature change causes the bimorph 100A to bend such that the first material outer surface 111 bends convexly and the second material outer surface 121 bends concavely.

The change in configuration of the bimorph 100A from the flat configuration (fig. 1 a) to the curved configuration (fig. 1 b) can occur in different ways. For example, table 1 shows five examples of how the configuration changes may occur.

	A first material (110)	A second material (120)
			1	Expand along L1	Without change
2	Expand along L1	L2 swell less than L1
			3	Expand along L1	Contract along L2
4	Without change	Contract along L2
			5	Contract along L2	L2 shrinkage was greater than L1

Table 1: exemplary reasons for the change in configuration of the bimorph 100 from the flat configuration (fig. 1 a) to the curved configuration (fig. 1 b).

In various embodiments, examples 1-5 of Table 1 may occur due to a positive or negative change in temperature. Thus, in some embodiments, the temperature rise may cause the first material 110 to expand or contract along L1. In other embodiments, the temperature drop may cause the first material 110 to expand or contract along L1. Similarly, in some embodiments, the temperature rise may cause the second material 120 to expand or contract along L2. In other embodiments, the temperature decrease may cause the second material 120 to expand or contract along L2. Additionally, in some embodiments, the first or

second materials

110, 120 may not expand or contract along their respective lengths L1, L2 due to temperature changes (positive or negative).

In some embodiments, the bimorph 100 can be configured to exhibit an area change of no more than 5% in response to a temperature change of 10 ℃. In other embodiments, the bimorph 100 can be configured to double its effective thickness in response to an environmental change of 10 ℃ or less.

Fig. 1a and 1b illustrate an exemplary configuration change, wherein the bimorph 100A bends such that the second material outer surface 121 becomes concave; however, in other embodiments, the bimorph 100A may assume another configuration (not shown) in which the second material outer surface 121 becomes convex and the first material outer surface 111 becomes concave. For example, in one embodiment, the bimorph 100A isXCan assume a flat configuration (FIG. 1 a) at (deg.C)X+Y) A curved configuration is assumed at a temperature of deg.c, wherein the second material outer surface 121 becomes convex (fig. 1 b). In addition, the bimorph 100A may be represented byX-Y) Exhibits a curved configuration at a temperature of a second material, wherein the second material is outer DEG CThe surface 121 is concave (not shown). In other words, in some embodiments, the bimorph 100 can bend in one direction and then in another direction based on temperature changes. Additionally, in various embodiments, the bimorph 100 can dynamically move back and forth between configurations based on temperature changes, as shown by the double-headed arrows.

Additionally, although various embodiments herein discuss the bimorph 100 changing based on a change in temperature, in other embodiments the bimorph 100 can change configuration based on one or more changing conditions, including humidity, exposure to light, exposure to chemicals, exposure to liquids (e.g., water), air pressure, applied forces (e.g., via wind or touch), magnetic field exposure, exposure to electrical current, and the like. Accordingly, the exemplary embodiments discussed herein should not be construed as limiting the wide variety of alternatives and other embodiments that are within the scope and spirit of the invention.

Fig. 2a is an illustration of an exemplary bimorph 100B having an alternating structure comprising first and

second materials

110, 120, wherein the first material 110 is shown in an alternating pattern on the opposite side of the second material 120 and coupled at respective coupling junctions 115. In this example, the two portions P1, P2 are defined by a respective pair of first and

second materials

110, 120 having opposed outer surfaces 111, 121. Figure 2 illustrates the bimorph 100B at a "flat temperature" where the bimorph 100B is in a flat and unbent configuration.

Fig. 2B shows the exemplary bimorph 100B of fig. 2a at different temperatures. In this example, the temperature change causes the bimorph 100B to bend in an "S" shape. More precisely, in the curved configuration of fig. 2b, the first and

second materials

110, 120 have been curved such that the second material outer surface 121 is concave and the first material outer surface 111 is convex. As discussed herein, the bending may result from various characteristics of the

materials

110, 120. Although fig. 2a and 2B illustrate one example in which an exemplary bimorph 100B includes two portions P1, P2 of alternating structures of first and

second materials

110, 120, in other embodiments such bimorph 100B may include any suitable plurality of portions P, and multiple bimorphs 100 may be combined into a bimorph structure.

For example, FIG. 3 shows a piezoelectric device including first and second bimorph wafers 100B₁、100B₂In a lofty state, an exemplary bimorph structure 300. Each elongated bimorph 100B shown in fig. 3 includes first, second and third portions P1, P2, P3 that include a first material 110 coupled on alternating sides of a flat elongated second material 120. The bimorph 100B is coupled at the

respective end

303, 304 and defines an inner cavity having a height H. In this example, the first and third portions P1, P3 are defined by the first material 110 disposed on the second material 120 within the facing cavity 350. The second portion P2 is defined by the first material 110 disposed on the second material 120 facing outwardly toward the respective top and

bottom sides

301, 302.

In the example shown in fig. 3, the bimorph 100B assumes a curved configuration based on ambient temperature, resulting in a lofty configuration of the structure 300, with the first bimorph curving centrally up toward the top end 301 and centrally down at the bottom end 302. However, in some embodiments, the bimorph 100B may experience different degrees of lofting based on temperature. In other words, the height H of the cavity 350 may expand or contract based on temperature changes.

Although the example shown in fig. 3 illustrates an exemplary structure 300 having a bimorph 100 with a finite width W, in other embodiments, the bimorph 100 can be an elongated flat sheet that can comprise a fabric or the like. Similarly, although fig. 3 illustrates an exemplary structure 300 having a bimorph 100 with three portions P1, P2, P3 coupled at ends 303, 304, in other embodiments, the bimorph 100 can comprise any suitable plurality of portions with opposing portions coupled at any selected spacing (regular or irregular). For example, in some embodiments, the bimorph 100 having multiple portions need not be coupled only at the

ends

303, 304, and may instead be coupled between the ends where multiple cavities 350 may be created.

Additionally, in some embodiments, the bimorph 100 can be coupled in any desired manner along the width and/or length of the bimorph 100 or can be coupled in any other desired regular or irregular pattern, which may or may not include coupling parallel to the length or width of the bimorph 100. Thus, as discussed in greater detail herein, in some embodiments, the bimorph structure 300 may define a flat sheet, which may comprise a fabric or the like, which defines a plurality of cavities of suitable size and shape. As discussed herein, such fabrics comprising bimorphs 100 and/or bimorph structures 300 can dynamically change configuration based on temperature, which can be desirable for a variety of purposes.

For example, in one embodiment, and referring to fig. 3, the bimorph structure 300 can change configuration such that the height H of the one or more cavities 350 increases with lower temperature, which can be desirable for dynamically creating insulation from a cold environment. In other words, the jacket, sleeping bag, blanket, bag, or other article may change configuration in response to exposure to cold in order to dynamically and gradually isolate the wearer or article from the cold. On the other hand, the height H of the cavity or cavities decreases with higher temperatures when exposed to heat, which may be desirable for dynamically preventing overheating of the wearer or the article in warm environments. In other words, where it is desired to maintain the wearer or the packaged article within a particular temperature range, various embodiments may be configured to dynamically provide varying degrees of thermal insulation based on changes in ambient temperature.

Fig. 4a and 4b show an exemplary bimorph structure 400 configured to bend along two axes. The exemplary bimorph structure 400 includes four bimorphs 100C, each bimorph 100C including triangular shaped first and

second materials

110, 120 stacked along a coupling surface 115. The bimorphs 100C are connected together in a rectangular parallelepiped configuration abutting at respective edges 415 and are coupled together at a central location 420. In various embodiments, the center location of the coupling may include a portion of the edge 415 adjacent to the center location 420. In this example, the opposing bimorph 100C in the structure 400 has the same material, 420, on the top and

bottom surfaces

401, 402.

Figure 4a illustrates a bimorph structure 400 in a flat configuration. Figure 4b illustrates a bimorph structure 400 in a curved configuration, wherein the opposing bimorph 100C with the second material 120 on the top surface 401 is curled upward creating a concave portion on the top surface 401. In addition, the opposing bimorph 100C having the second material 120 on the bottom surface 402 curls downward to create a concave portion on the bottom surface 402. As discussed herein, the structure 400 may be varied between the configurations of fig. 4a and 4b based on temperature changes.

A variety of similar geometries, configurations, and cut-outs may be provided in other embodiments to achieve similar geometric variations. For example, other embodiments may include any suitable plurality of bimorphs 100 arranged about a central location 420. The shape of the bimorph 100, and the overall structural shape produced by such bimorphs, can be any suitable regular or irregular shape.

In various embodiments, such structures may act as loose thermally adaptive fillers. To achieve large thickness variations from the multiple layers of such a single bimorph layer structure 400, it may be advantageous in some embodiments to have multiple similar, but not identical structures to prevent the cup-shaped three-dimensional shapes from nesting in each other. The varying three-dimensional structure may serve as an organizational constraint for the multi-scalar structure. In some embodiments, a plurality of the bimorphs 400 can be disposed in the cavity 350 (fig. 3) as described above. Fig. 5a and 5b illustrate examples of how the bimorph 100A of fig. 1a and 1b can be used in multiple instances as a loose thermally adaptive filler, or the like.

Figure 6a shows an exemplary helical bimorph structure 600 at a flat temperature. The bimorph structure 600 can include two

materials

110, 120 that can be joined together and can have the same general or segmented pattern. In this example, the substantially continuous second material 120 is present in a rectangular shape defining a central cavity 605, while portions of the first material 110 are disposed in an alternating configuration on opposite sides of the second material 120. In some embodiments, the structure 600 may exhibit geometric variations along more than one axis.

FIG. 6b shows a coiled or convoluted structure 600 undergoing displacement in response to temperature changes; the end of the first arm 610 of the structure 600 is raised relative to the second arm 615, which second arm 615 may serve as a base in some embodiments. The first and

second arms

610, 615 may be considered the ends and open ends of the bimorph structure 600, but alternatively a thermally non-responsive pad may be introduced into the first arm 610, or the second arm 615 may be composed of only one of the

materials

110, 120 such that it will not undergo any bending in response to temperature changes. Additionally, in one embodiment, the

arms

610, 615 may have different shapes such that they may act as pads connected with other bimorphs or bimorph structures. In a separate layer, the bimorph structure 600 can be directly connected to other bimorph structures by thin tethers or the like such that an interconnecting sheet, film or membrane is created.

The exemplary structure 600 in fig. 6a and 6b is shown with a cavity at the center, but there are a variety of alternative coil or spiral structures that may be provided in other embodiments, both with and without holes introduced for the porous structure. A variety of similar geometries and structures may be provided in other embodiments that may be fine tuned for specific applications, including structures similar to flat coil springs (plane springs) or face springs (diaphragm springs).

Additionally, exemplary structure 600 is illustrated as having a portion 620 in which second material 120 is stacked between two pieces of first material 110, and also having a portion 625 bounded by the stack of monolithic pieces of first and

second materials

110, 120. In various embodiments, a portion 620 having a stack of three or more materials may create a "flat zone" in structure 600 that does not bend in response to temperature changes, even if other portions bend. This may be because any changes in the top and bottom materials of the same stack may cancel each other out in that portion of structure 600 and thus cause no bending in that portion 620. Although portions 620 having a stack of three materials are shown at the corners of exemplary structure 600, in other embodiments, the portions 620 may be present at any suitable portion of a given structure. Similarly, in some embodiments, the portion 625 defined by the pair of

stacked materials

110, 120 may also be present at any suitable location of the bimorph structure.

In some embodiments, the coiled or spiral structure 600 does not itself introduce geometric constraints that make it ideal for a multilayer structure. However, by using multiple geometries with similar temperature-displacement responses but varying specific convolutions, sheets of interconnected coils or helical structures may not be able to easily tangle or move into the open space left by the temperature-responsive bimorph. This type of spiral-shaped structure may serve as a component in a multilayer thermally adaptive structure according to other embodiments.

Fig. 7 shows a top or plan view of a structure 700 comprising four exemplary dual-layer bimorphs 100 interconnected in a repeating patch or unit cell form that can be used to fabricate bimorph sheets. One of the materials is shown in shadow and serves as a substrate in this exemplary embodiment. The solid lines represent the lines through the material, the dashed lines represent the ends of the top material, which is unshaded, on top of the substrate material, and the dotted lines represent the edges of the structure 700. The overall structure 700 can be a repeating unit cell, creating a large sheet of interconnected bimorphs.

The bimorph region is here divided into four bimorph cantilevers 100, and each of the four cantilevers can move out of plane at the center of the structure in response to temperature changes. The region shown with only the substrate material 120 (shaded) may act as a flexible tether or connector between the bimorph 100 of this cell and the adjacent cell. In some embodiments, this connection need not have a temperature-bending response. This connection between the bimorphs can produce a flexible sheet with a temperature responsive thickness.

To achieve large thickness variations, a multilayer structure may be desirable in various embodiments. A multi-scalar sequence may be introduced between layers, such as by alternating the direction of each layer such that each other layer is orthogonal to the layer immediately above and the layer immediately below, such as the sequence shown in fig. 7. The bottom of a layer stands on the orthogonal bimorph of the layer below, and the rising bimorph of a layer acts as a support for the orthogonal bottom of the layer above. In view of the aspect ratio of the bimorph regions, in various embodiments, orthogonal rotation between the layers causes each layer to span at least two bimorph regions in the layer below it, ensuring that the bimorphs from one layer are supported by the layer below and do not fall into the void space created by the geometric changes of the bimorphs.

In addition to the interlayer order created by the orthogonal orientation of one layer relative to another, the illustrated exemplary structure may have flexible tethers in its unit cell structure that connect the individual bimorphs together side-by-side in an elongated sheet. A sheet structure such as this may be advantageous because it is less likely to bunch up or fall via gravity to the bottom of the quilted bag, which is instead still in a flat sheet at higher temperatures. The in-plane or in-sheet sequence prevents the adaptive insulating material from clumping or caking.

The flexibility of the tether can be controlled by varying the width and convoluted path of the interconnect. Although a single-sided bimorph active region is shown, in other embodiments there may be a double-sided bimorph geometry, with the interlayer and intralayer order discussed above. In general, the geometry of the layers and the orthogonal arrangement of the layers in the multilayer structure can provide mechanical coupling between the bimorph layers.

A foil structure similar to those of fig. 7 can have intra-flex layer interconnects between individual bimorphs, and other bimorph structures can be interconnected in a similar manner. However, some embodiments include a foil structure that may not require an interconnect space to connect the bimorphs. One such structure consists of an array of dots on a substrate, with concentric rings of the same material on the other side of the substrate, forming a double-sided bimorph with a ring-shaped structure. Such materials can form concave surfaces with temperature changes, thickness changes resulting from material deformation along two axes. Although flexible tethers could be used between active regions of such recessed surfaces, the circular structures could be arranged in such a way as to place the bimorph region at maximum surface density and the interconnects could be directly between adjacent ones.

In some embodiments, the recessed structures, and indeed, the plurality of sheet structures, may have undesirable breathability due to the non-porous structure. Thus, in various embodiments, small holes or slits may be introduced into these multilayer structures to provide opportunities for increased vapor transport and evaporation. Additionally, temperature responsive geometric changes in the multilayer structure can be used to increase or decrease porosity.

The alignment and alignment of one bimorph with respect to another bimorph may be desirable in some embodiments for the effective temperature response of the multi-layer set of bimorphs. This sequence may be achieved by joints or bonding, as shown in fig. 3, or by mechanical constraints imposed by the geometric design and positioning of each of the layers, as shown in fig. 7. Methods, such as weaving, can likewise be suitable for introducing the sequence into the multilayer structure such that the two bimorph regions overlap and their individual temperature-dependent thicknesses add together in an optimized manner. These multilayer structures can be constructed from individual layers of complex bimorphs containing one, two, or more sides, mechanically amplified structures, or actuation mechanisms that do not include bimorphs. In various embodiments, the porosity and flexibility of each individual layer may be controlled by holes, slits, or convoluted helical structures, etc. within the layer.

Figures 8a and 8b illustrate a bimorph structure 800 comprising upper and lower bimorphs 100U, 100L coupled at respective ends 801, 802. In this example, the upper bimorph 100U is shown to contain a plurality of vertically oriented lines 810V and the lower bimorph 100L is shown to contain a plurality of horizontally oriented lines 810H. Fig. 8a illustrates an open configuration of the bimorph structure 800, wherein the bimorph 100 forms a cavity 850 separating the respective lines 810 on the upper and lower bimorphs 100U, 100L. Figure 8b illustrates a closed configuration of the bimorph structure 800, wherein the bimorphs 100 are in contact and the cavity 850 is substantially absent. In fig. 8b, horizontal and vertical lines 810H, 810V are shown touching or in close proximity.

In various embodiments, the metal nanowire mesh structure can produce reflectivity in the thermal infrared region. In an example of textile applications, a garment containing such a nanowire mesh structure can insulate the garment by reflecting heat energy back to the wearer of the garment.

In the case of fig. 8a and 8b, in some embodiments, the bimorph structure 800 can dynamically provide insulation by changing the configuration to produce a thermal infrared reflective mesh 860 as shown in fig. 8b, and by isolating the thermal infrared reflective mesh 860 by isolating the wires 810 as shown in fig. 8 a. In other words, when the respective lines 810 of the upper and lower bimorphs 100U, 100L are coupled as shown in fig. 8b, the bimorph structure 800 can produce reflectivity in the thermal infrared region, while when the respective lines 810 of the upper and lower bimorphs 100U, 100L are spaced as shown in fig. 8a, the thermal infrared reflection characteristics of the bimorph structure 800 can be removed.

Thus, in various embodiments, it may be desirable for the configuration shown in FIG. 8a to be generated at warmer temperatures, and for the configuration shown in FIG. 8b to be generated at cooler temperatures. In embodiments in which the bimorph structure 800 is present in a garment, this property can automatically help prevent the wearer of the garment from overheating at warm temperatures by transmitting thermal infrared heat through the garment in warm conditions, and can automatically help contain thermal infrared heat in cold conditions.

Thus, the bimorph structure 800 as shown in fig. 8a and 8b can be configured for use in a variety of articles of manufacture, including clothing, blankets, sleeping bags, tents, and the like. Additionally, the exemplary structures shown in fig. 8a and 8b should not be construed as limiting the wide variety of embodiments that are within the scope and spirit of the present invention. For example, the wires 810 may comprise any suitable material and may be oriented in a variety of suitable directions. In addition to reflectivity, the absorption of some materials can also change when they are very close to their neighbors, enabling this type of bimorph structure to enhance the reflectivity and absorption characteristics of the material, affecting the overall thermal insulation characteristics of the bimorph material. Alternatively, the optical properties of some materials or patterned structures, such as diffraction gratings, can be changed by physical deformation or stretching, and integration with bimorph structures can produce temperature-sensitive optical absorption and reflection properties.

Bimorphs and bimorph structures can be made in a number of suitable ways. Fig. 9a illustrates an exemplary apparatus 900 and a method for manufacturing a bimorph 100D. The apparatus 900 comprises a first spool 905 having a coiled sheet of the first material 110 and a second spool 910 having a coiled sheet of the second material 120. The apparatus 900 further includes a cutter 915 that cuts the sheet of the first material 115 longitudinally into a plurality of strips of the first material 110. The upper and lower spacer bars 920U, 920L divide the plurality of strips of the first material 110 into a set of upper and lower strips 110U, 110L defining a strip cavity 925 between the set of upper and lower strips 110U, 110L of the first material. A second spool 910 of the second material 120 is disposed in the strip cavity 925. In this example, the groups of strips 110U, 110L are created by separating adjacent strips after the strips of first material 110 are cut such that each even-numbered strip becomes an upper strip 110U and each odd-numbered strip becomes a lower strip 110L. Alternatively, the upper and lower strips 110U and 110L may comprise fibers, threads, yarns, or ribbons from separate rolls.

The sheet of second material 120 extends from the second spool 910 and through a set of rollers 930U, 930L. The first strips of material 110U, 110L also pass through rollers 930U, 930L and are coupled to the top and bottom surfaces, respectively, of the sheet of second material 120 to define the bimorph 100D. In various embodiments, the first and

second materials

110, 120 may be coupled together in any suitable manner, including via welding, lamination, fusion, adhesives, stitching, and the like.

Figure 9b illustrates a close-up perspective view of the edge of the bimorph 100D produced by the apparatus 900. As discussed above, the upper strip 110U is shown disposed on the top surface of the second material 120, offset from the lower strip 110L disposed on the bottom surface of the second material. In various embodiments, the bimorph 100D can have similar characteristics to those of the bimorph 100B shown in fig. 3, and the bimorph 100D foils shown in fig. 9a and 9B can be used to produce the bimorph structure 300 shown in fig. 3, and so on.

In various embodiments, it may be desirable for the bimorph sheet 100D to include perforations, slits, or the like. Such structures may be desirable for breathability flexibility and/or stretchability. In some embodiments, the substrate 120 may be perforated or may be a porous woven, knitted, or non-woven material. In some embodiments, controlled perforation may be desirable for allowing the bimorph 100 to operate in a preferred direction for uniaxially or biaxially oriented polymers (in such materials, CTE, modulus, and strength values may all be anisotropic and a particular direction may be preferred). Some embodiments may include a method of making a double-sided bimorph structure with offset perforated or perforated top and bottom layers that enables alignment of a preferred direction of the layer 110, the layer 110 comprising top and bottom portions of alternating bimorphs. In one embodiment, the material 110 is not cut into two strips but, instead, is perforated or perforated such that it has a striped structure with solid portions connected by perforated regions. The perforated material 110 may then be applied to either or both sides of the second material 120. The perforations or perforations may be produced in a pattern that may extend in a roll-to-roll longitudinal direction or perpendicular to the longitudinal direction or in any other suitable direction. In some embodiments, perforated material 110 may be advantageous because it may be easily handled with mechanical equipment, is suitable for roll-to-roll and sheet processing, and it may enable the selection of preferred locations in the film for optimal bimorph performance.

In some embodiments, the plurality of bimorph foils 100D can be configured in such a way that the foil thickness variations add together to produce a thicker structure with a wide range of temperature responsive motion. In various embodiments, the bimorph 100 described herein can be laminar and configured such that the layers are stacked orthogonally to one another, creating geometric constraints between the layers that can prevent the layers from settling or nesting in one another, forcing each of the layers to "build" on or "lift" off the layer below it. Orthogonal rotation is merely one exemplary embodiment, and other angles of rotation may exist in other embodiments. In various embodiments, such layer-by-layer rotational configurations may avoid inter-layer connections, such as welds; however, in some embodiments, the separate layers may be coupled together via adhesives, welds or lamination, stitching, or the like.

Fig. 10 shows an embodiment of a roller 1000 having an undulating surface pattern 1001 configured for use in making the flat bimorph structure 100E shown in fig. 10 and 11. In various embodiments, the bimorph structure 100E can be configured to be flat at a desired temperature or over a range of temperatures. In a preferred embodiment, this temperature or temperature range may correspond to the skin or core temperature of a human or animal subject.

In various embodiments, the roller 1000 and surface texture or pattern 1001 may be configured to provide a controlled curvature of the bimorph 100E at the temperature of heat setting, lamination, adhesion, or polymer welding, such that the bimorph sheet 100E may achieve a flat structure when the temperature is reduced to ambient or skin temperature.

In some embodiments, the pattern dimensions of the bimorph 100 can be in the millimeter range, sub-millimeter range, or have other desired sizes. Additionally, such patterns may cover one or both sides of the substrate, which may be in a variety of thicknesses, including about 1 μm, 10 μm, 100 μm, and so forth. In various embodiments, each side of the bimorph 100 can be aligned with the other side. In some embodiments, ink jet printing, screen printing, and similar wet techniques can be used on the bimorph 100.

In another embodiment, the first and second materials 110, 120 (e.g., polymers) may be laminated together. The laminated bimorph 100 can comprise a center of the second material 120, a continuous sheet, and the first material 110 in a series of parallel narrow strips on one or both sides of the second material 120. For example, such structures are illustrated in fig. 9a and 9b (strips of first material 110 on both sides of second material 120) and in fig. 11 (strips of first material 110 on a single side of second material 120).

In some embodiments, one or both of the first and

second materials

110, 120 may comprise or be produced from a continuous sheet having perforations in certain areas, rather than discrete ribbons or strips. Such embodiments may be desirable because they may simplify manufacturing compared to multiple discrete strips or ribbons.

As discussed herein, it may be desirable to create a structure of a bimorph 100 via layering a plurality of bimorphs 100. In some embodiments, the respective layers may or may not be physically coupled or connected.

For example, in one embodiment, bimorph 100 sheets according to various embodiments can be stacked orthogonally with their corrugations extending in different directions. This can result in a structure having a desired variation in thickness or bulk. In such embodiments, there may or may not be layer-to-layer connections or alignments.

Bimorph fabrication can be challenging due to the dynamic changes in the material due to temperature changes, as the neutral or flat temperature (the temperature at which the bimorph is flat) can be difficult to control, depending on the material and fabrication method. For example, thermal welding of materials may cause a flat temperature at the temperature of the weld, which may be undesirable in some embodiments. Thus, in some embodiments, a roller 1000 (fig. 10, 11) having an undulating surface pattern 1001 may be desirable for laminating a ribbon, strip, or sheet, and may provide a manufacturing means that accompanies bending or buckling of the material so that as it cools, the material flattens out to a desired neutral or flat temperature.

Thus, at the level of bimorph construction or processing, a shaped or patterned roller 1000 used for roll-to-roll processing or lamination of tapes, ribbons, perforated sheets, textiles, and the like, may be desirable for controlling the flat or neutral temperature of the bimorph, bimorph sheet, or bilayer structure. Additionally, in some embodiments, the use of a perforated or perforated sheet may allow for roll-to-roll processing of the bimorph 100 or bimorph sheet, wherein the preferred orientation direction of the polymer film or the like is aligned in the critical dimension of the bimorph 100 or sheet. Such orientation may be desirable due to anisotropic properties (e.g., CTE, modulus, strength, etc.). Such bimorph sheets can also be set to have a flat or neutral temperature by controlled temperature, tension, curvature and pressure contact area during thermal welding or bonding of the first and

second materials

110, 120.

Fig. 11 illustrates a bimorph 100E produced by top and bottom rollers 1000A, 1000B each having opposing undulating surfaces 1001. In this example, the bimorph 100E includes a second material 120 including a concave portion 1010 and a convex portion 1015 relative to the top surface of the bimorph 100E. On the top surface of the bimorph 100E, the first material 110 is disposed in the concave portion 1010 of the second material 120.

In the example of fig. 11, the top and bottom rollers 1000A, 1000B can provide heat and/or pressure, which can create concave and

convex portions

1010, 1015 in the bimorph 100E and/or can couple the first and

second materials

110, 120.

The difference in Coefficient of Thermal Expansion (CTE) is a term that can indicate a range of motion or deflection of the bimorph 100. For some materials, the term Δ CTE may be 100-. Accordingly, various embodiments of bimorphs can include a highly twisted polymer wound actuator 1210 (e.g., fig. 12a, 12b, 13a, 13b, etc.), which in some embodiments can have an effective CTE value of 1000 μm/m/K or more. Such CTE values can be used in bimorph and bilayer structures having desirable flexural or bending characteristics. Any material with a particularly large CTE value may be suitable for this approach, not just a twisted polymer wound actuator.

In various embodiments, the winding actuator 1210 can act as a thermally responsive tension actuator (linear motion) and/or a torsion actuator (rotational motion). In other embodiments, the structures described herein convert the linear motion of the winding actuator 1210 into motion in an orthogonal direction through the use of supplemental materials. The embodiments may be desirable for use in thermally responsive yarns, padding, felts, fabrics, and the like, which may include garments and other articles that thicken upon exposure to low temperatures.

In various embodiments, it may be desirable to pair materials where the difference between the CTE values of the two paired materials is large. Therefore, a coiled actuator 1210 with a large CTE value may be desirable for use in bimorphs 100 and structures containing bimorphs 100. In some embodiments, the coiled actuator 1210 can have positive CTE characteristics (e.g., expansion with increasing temperature, heterochiral coils, where the twist and coil directions are opposite) or large negative CTE characteristics (e.g., contraction with increasing temperature, homochiral coils, where the twist and coil directions are the same). In various embodiments and as described herein, the pair of opposing coiled actuators 1210, including their filament materials together, can produce a larger acte.

In various embodiments, the bimorph 100 can comprise a twisted coil actuator 1220, wherein linear displacement of the actuator due to temperature changes can induce out-of-plane or orthogonal flexure of the bimorph 100, causing an effective change in the height or thickness of the bimorph 100.

Fig. 12a and 12b illustrate an exemplary bimorph 100F including a coiled actuator 1210 and a filament 1220 coupled at first and

second ends

1230, 1240. The coiled actuator 1210 and the filament 1220 can be coupled only at the first and

second ends

1230, 1240 and/or can be coupled along a portion of their lengths.

In various embodiments, the wrap actuator 1210 may expand or contract longitudinally in response to temperature changes. For example, the winding actuator 1210 can contract when cooled (hetero-chiral fiber actuator, with opposite twist and coil directions) or expand when cooled (homo-chiral fiber actuator, with same twist and coil directions). In various embodiments, filaments 1220 may expand, contract, or exhibit no significant change in the machine direction.

Figure 12a illustrates the bimorph 100F in a flat configuration at a first temperature on the left and a first contracted configuration caused by a change in temperature on the right. Figure 12b illustrates the bimorph 100F of figure 12a in a flat configuration at a first temperature on the left and a second contracted configuration caused by a temperature change opposite to that shown in figure 12a on the right. For example, fig. 12a may illustrate a change in configuration based on a negative temperature change, and fig. 12b may illustrate a change in configuration based on a positive temperature change.

In various embodiments, the coiled actuator 1210 and the filament 1220 can be configured to be curved, as shown in the exemplary embodiment of fig. 12a and 12b, wherein the lengths of the coiled actuator 1210 and the filament 1220 are butted in a curved and straight configuration. In other embodiments, the coiled actuator 1210 and the filament 1220 can be configured to bend differently, and the coiled actuator 1210 and the filament 1220 may not abut in a flat and/or bent configuration.

For example, fig. 13a illustrates an exemplary embodiment of a bimorph 100G having a coiled actuator 1210 and a filament 1320, wherein the coiled actuator 1210 maintains a linear configuration when the bimorph 100 is in a flat configuration (left) and a curved configuration (right). In this example, the winding actuator 1210 exhibits shrinkage due to temperature changes, which cause the filament 1320 to bend away from the winding actuator 1210.

Similarly, fig. 13B illustrates a bimorph 100H including first and second filaments 1320A, 1320B and a coiled actuator 1210 between the first and second filaments 1320A, 1320B. In this example, the bimorph 100H shows shrinkage due to temperature changes, which causes the filaments 1320A, 1320B to bend away from the coiled actuator 1210, while the coiled actuator 1210 maintains a linear configuration.

Fig. 14a and 14B illustrate exemplary bimorphs 100I, 100J including first and second coil actuators 1210A, 1210B coupled at first and

second ends

1230, 1240. In some embodiments, the winding actuators 1210A, 1210B may be coupled along a portion of their length. Fig. 14a illustrates an exemplary embodiment in which the coiled actuators 1210A, 1210B have opposite thermal responses and remain in abutment in the flat configuration (left) and the curved configuration (right). In contrast, fig. 14B illustrates an exemplary embodiment in which the coiled actuators 1210A, 1210B are contiguous in a flat configuration (left) and separable in a curved configuration (right).

Fig. 15 illustrates an exemplary embodiment of a bimorph 100K with a coiled actuator 1210 and a filament 1220, wherein the filament 1220 maintains a linear configuration when the bimorph 100 is in a flat configuration (left) and a curved configuration (right). In this example, the coiled actuator 1210 exhibits expansion due to temperature changes, which causes the coiled actuator 1210 to bend away from the filament 1220.

In various embodiments, one or more twisted coil actuators 1210 coupled with one or more stiff opposing filaments 1220 can act as a fixed structure, relative to which coil actuators 1210, the expanded coils 1210 can be orthogonally displaced, resulting in a structure with little linear expansion that still changes its effective thickness. Fig. 15 illustrates one example of such a structure.

In addition to the desired effective CTE value, the coiled actuator 1210 may also provide some processing or manufacturing advantages, such as mechanical connection pathways not available in sheet structures, and the advantages of manufacturing positive and negative CTE coils from the same length of material as discussed herein. When the spring constant of the winding actuator 1210 is large when the length of material is wound around a mandrel, the effective CTE value of the winding actuator 1210 can be maximized, leaving an open space at the center of the coil. The wrap actuator 1210 may also be desirable due to porosity, density, and breathability, among other things, which may be present in such structures.

Fig. 16 illustrates a dual mandrel structure 1600 for manufacturing a wrap actuator 1210 having alternating achiral and homochiral regions 1610, 1620 that can respond in an opposite manner to temperature changes, which can produce a wrap actuator 1210 with little linear variability while maintaining the ability to laterally deform and the change in effective thickness. The structure 1600 is shown to include first and second mandrels 1610A, 1610B with a winding actuator 1210 winding about each mandrel 1610A, 1610B in opposite directions. 1

Alternating heterochiral and homochiral regions in the same fiber actuator can also be created by twisting the fiber at its center with force while keeping the two ends under tension, creating portions of the fiber that are twisted in opposite directions. At this point, the fiber is wound around a single mandrel and the resulting coil will have regions of heterochirality and homochirality, resulting in a length of material having alternating contracting and expanding segments.

In various embodiments, materials having greater deflection and less linear deformation may be produced by alternating contracted and expanded segments within the same filament in a yarn (or as separate elements). For example, a wrap actuator 1600 as shown in fig. 16 may be included in a fabric, yarn, or other material. Alternatively, the use of short fibers (some expansion, some contraction) may produce a material with less linear deformation.

In various embodiments, the coiled actuator 1210 can be woven or stitched through a fabric or film to create a bimorph sheet structure, as described in more detail herein, with large effective delta CTE values and correspondingly large deflections. In other embodiments, the coiled actuator 1210 can be stitched or bonded to a sheet to create a bimorph sheet. In some embodiments, a winding actuator 1600 (e.g., as shown in fig. 16) having alternating curling segments and alternating expansion and contraction segments with opposite chirality can be stitched or bonded to a surface of a sheet or fabric. A sheet structure can be formed in which the sheet or ribbon is sinusoidal with temperature variation due to the positive and negative thermally responsive regions in the alternating chiral coiled actuator 1600. Embodiments of the alternating chiral wrap actuator 1600 may be used in a variety of applications. For example, various embodiments may be configured for use in manufacturing thermally adaptive garments in which alternating chiral coils may be used in a conventional lockstitch (lockstitch) to create alternating positive and negative CTE regions on the surface of a fabric, causing the fabric to fluctuate with temperature. In some embodiments, the second yarn or fiber in the lock stitch need not be a large CTE or twist coil actuator material.

In some embodiments, multiple coiled actuators 1210 can be arranged side-by-side and woven or stitched together, resulting in a sheet or layer with a desired CTE in a single direction. In yet further embodiments, such sheets with different CTEs (e.g., one with a large positive CTE and one with a large negative CTE) may be paired to produce a flat bimorph sheet with a desired difference in thermal expansion and a desired radius of curvature.

In other embodiments, the wrap actuator 1210 can be sewn onto a film, membrane, or fabric, which can impart a thermally responsive property to such film, membrane, or fabric. Thus, various embodiments may eliminate the need for more in-depth integration of selected materials with insulating materials or fabrics. In such embodiments, the thermally responsive material may additionally be a portion of a fabric, it may be the body of the insulating material, it may be a substrate, or it may be bonded to another material by an adhesive or thermal adhesive.

In another embodiment, a net-zero CTE material may be comprised of such alternating chiral coiled actuators 1600, where the sum of the positive and negative CTE regions add to produce a zero total variation.

In addition, the winding actuator 1210 may be used to create a branched structure similar to that in goose down. For example, in some embodiments, in the context of larger variable insulation materials, thin fibers may be collected or captured in coils by pulling the twisted fibers through a thin fiber layer during winding, forming a branched structure with advantageous thermal insulation, feel, and structural properties.

The winding actuator 1210 can act as a linear or torsional actuator. In various embodiments, pairing two different materials may produce out-of-plane or orthogonal motion, as discussed herein. In some embodiments, a woven or knitted structure that pairs twisted coils having different CTE characteristics in an opposing manner may comprise a thermally responsive bimorph 100. In some embodiments, the multiple materials may be woven together in a variety of suitable ways to create an overall physical structure of the fabric that changes in response to temperature. Such braided structures may include a coiled actuator 1210 or other suitable material or structure that changes configuration or length in response to temperature.

In various embodiments, the woven or knitted structure may act as a constraint by aligning the fibers such that the overall motion is cohesive and not characterized by random individual twisting of different fiber groups, which may be desirable for thermally adaptive materials and maximize their deflection or their effective thickness variation.

In other embodiments, the temperature-sensitive structure may include a non-adaptive constraint, such as a fiber, yarn, or fabric that opposes the active material, where the non-adaptive material remains linear or flat and the active material bulks due to expansion, or where the active material remains linear, or flat and the non-adaptive material bulks due to contraction of the active material. The desired temperature response can be produced in such structures by appropriate constraints of weaving, knitting, or the use of adhesives. In some embodiments, it may be advantageous to employ constraints that limit the range of motion of the material.

Additionally, as discussed herein, the materials used to create the bimorph 100 can be responsive to one or more suitable environmental conditions, including humidity and/or exposure to liquid (e.g., saturation by liquid). For example, in some embodiments, it may be desirable for the adaptive thermal insulation material in the garment to respond to temperature changes and humidity changes (e.g., based on the user's moisture and/or perspiration). Thus, the use of humidity sensitive polymers and other suitable materials in a variety of bimorph structures can be configured to have temperature and humidity responsiveness. Such materials may react primarily to humidity or chemical stimuli.

Fig. 17 illustrates an exemplary embodiment of a thermally adaptive braided structure 1700. In this example, the structure 1700 may be configured to define fibers having different thermal expansion characteristics to create a thermally responsive textile, wherein the geometric change is not in the plane of the fabric, but perpendicular to the plane, effectively changing the fabric thickness.

The structure 1700 is shown to include first and

second fibers

1710, 1720, which may have different coefficients of thermal expansion. More specifically, the first fibers 1710 can have a different coefficient of thermal expansion relative to the parallel extending second fibers 1720, which can result in an alternating bimorph structure. The upper and lower crossing fibers (or yarns) 1730, 1740 help to maintain the shape of the structure 1700 and/or constrain the first and

second fibers

1710, 1720. According to some embodiments, the

crossing fibers

1730, 1740 may or may not change shape or length in response to temperature changes. In various embodiments, the structure 1700 behaves as an alternating bimorph structure as in fig. 2 and 3, and can exhibit a wave-like structure (e.g., similar to a corrugated sheet) because temperature changes can cause different expansions and contractions along the length of the parallel and opposing first and

second fibers

1710, 1720. The passing fibres need not have any particular thermal characteristics, but their role in constraining the parallel and opposed fibres is crucial, which is the main cause of the overall geometric deformation in response to external stimuli.

Fig. 18a and 18b illustrate a thermally responsive woven structure 1800 in a bag or quilted that shows lofting in response to an increase in temperature. Fig. 18a illustrates the structure at about 25 deg.c, and fig. 18b illustrates the structure at about 65 deg.c. In this example, the heat may cause the structure 1800 to loft, however in other embodiments, the structure 1800 may be configured to loft in response to a decrease in temperature, as discussed herein.

Fig. 19a and 19b illustrate a thermally responsive braided structure, which shows lofting in response to a decrease in temperature. Fig. 19a illustrates a substantially flat textile structure at 30 ℃, and fig. 19 illustrates a lofted structure at 7 ℃.

Embodiments of the woven or knitted structures described herein may be advantageous in that they may utilize existing base structures and manufacturing methods. Other embodiments may desirably avoid the use of adhesives and/or thermal bonding, techniques that may increase weight, induce physical deformation, or alter the properties of the materials of some embodiments. Additionally, the embodiments of woven or knitted structures discussed herein may also allow for the introduction of other companion fibers that may provide advantages for a compliant textile, such as fibers for wicking for moisture management, fibers for abrasion resistance, fibers for feel or hand, and the like.

The described embodiments are susceptible to various modifications and alternative forms, and specific examples thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the embodiments are not to be limited to the particular forms or methods disclosed, but to the contrary, the intention is to cover all modifications, equivalents, and alternatives.

Claims

1. A thermally adaptive garment configured for wearing on and encircling a user's body, the thermally adaptive garment comprising:

a garment body defined by a thermally adaptive fabric, the thermally adaptive fabric comprising:

a first fabric layer;

a second fabric layer coupled to the first fabric layer at one or more seams; and

a plurality of cavities defined by and disposed within the first and second fabric layers and the one or more seams;

wherein the first fabric layer is configured to assume a base configuration responsive to a first ambient temperature range, wherein the first fabric layer is spaced from the second fabric layer by a first average distance; and is

Wherein the first fabric layer is configured to assume a lofted configuration responsive to a second ambient temperature range different from the first ambient temperature range, wherein the first fabric layer is spaced from the second fabric layer by a second average distance that is greater than the first average distance;

wherein the first fabric layer comprises a first material defining a first length, and wherein the first material is configured to gradually expand along the first length in response to temperature changes within the second ambient temperature range according to a first coefficient of thermal expansion having a magnitude greater than 1000 μm/m/K, and wherein the first material comprises a twisted polymer wound actuator;

wherein the first fabric layer comprises a second material defining a second length parallel to the first length, and wherein the second material is configured to gradually expand or contract along the second length in response to temperature changes within the second ambient temperature range according to a second coefficient of thermal expansion that is different from the first coefficient of thermal expansion;

wherein the difference between the first average distance and the second average distance is generated based at least in part on a difference in coefficient of thermal expansion (aCTE) between the first coefficient of thermal expansion and the second coefficient of thermal expansion.

2. The thermally adaptive garment of claim 1, wherein an average distance between the first and second layers increases in response to a temperature within the second ambient temperature range when ambient temperature increases different than the first ambient temperature range.

3. The thermally adaptive garment of claim 2, wherein the increased average distance between the first and second layers is limited to a maximum distance by a physical configuration of the garment body.

4. The thermally adaptive garment of claim 1, wherein the temperature of the second ambient temperature range is less than the temperature of the first ambient temperature range.

5. The thermally adaptive garment of claim 1, wherein the second fabric layer is configured to exhibit a second layer base configuration responsive to a third ambient temperature range, and wherein the second fabric layer is configured to exhibit a second layer lofting configuration responsive to a fourth ambient temperature range different from the third ambient temperature range.

6. The thermally adaptive garment of claim 1, wherein the first and second materials define respective first and second widths perpendicular to the first and second lengths, and wherein the first and second widths remain unchanged in response to temperature changes within the second ambient temperature range.

7. The thermally adaptive garment of claim 1, wherein at least one of the first or second coefficients of thermal expansion is negative.

8. A thermally adaptive fabric, comprising:

a first fabric layer defining a first length, the fabric layer configured to assume a flat base configuration responsive to a first ambient temperature range and assume a lofted configuration responsive to a second ambient temperature range, wherein the fabric layer curls along the first length as compared to the base configuration, the fabric layer comprising:

a first material defining a second length and having a first coefficient of thermal expansion greater than 1000 [ mu ] m/m/K in size, and wherein the first material is configured to gradually change length along the second length in response to temperature changes within the second ambient temperature range, an

A second material defining a third length and having a second coefficient of thermal expansion different from the first coefficient of thermal expansion,

wherein the first and second coefficients of thermal expansion define a difference in coefficients of thermal expansion (aCTE) indicative of a series of movements or distortions of the fabric layer of the thermally adaptive fabric;

the first fabric layer is coupled to a second fabric layer to form the thermally adaptive fabric.

9. The thermally adaptive fabric of claim 8, wherein the first material comprises at least one wrap actuator comprising alternating achiral and homochiral portions configured to respond in opposite ways to temperature changes, respectively.

10. The thermally adaptive fabric of claim 8, wherein the first fabric layer is configured to exhibit an area change of no more than 5% in response to a temperature change of 10 ℃.

11. The thermally adaptive fabric of claim 8, wherein the first and second materials combine to form a woven thermally adaptive fabric.

12. The thermally adaptive fabric of claim 8, wherein the first material comprises coils configured to contract or expand along the first length.

13. The thermally adaptive fabric of claim 8, wherein the first material comprises a flat sheet.

14. An adaptive sheet, comprising:

a first layer defining a first length, the first layer configured to assume a base configuration responsive to a first environmental condition and assume a lofted configuration responsive to a second environmental condition, wherein the first layer curls along the first length as compared to the base configuration, the first layer comprising:

a first material defining a second length and having a first coefficient of expansion greater than 1000 [ mu ] m/m/K in size, and wherein the first material is configured to change length along the second length in response to the second environmental condition, an

A second material defining a third length and having a second coefficient of expansion different from the first coefficient of expansion,

wherein the first and second coefficients of thermal expansion define a difference in coefficients of thermal expansion (aCTE) that is indicative of a sequence of movements or distortions of the layers of the adaptive sheet;

the first layer is coupled to a second layer for operation.

15. The adaptive sheet of claim 14, wherein the first environmental condition comprises a first temperature range and the second environmental condition comprises a second temperature range different from the first temperature range and comprises a temperature less than the first temperature range.

16. The adaptive sheet of claim 14, wherein the first environmental condition comprises a first humidity range and the second environmental condition comprises a second humidity range different from the first humidity range.

17. The adaptive sheet of claim 14, wherein the first layer comprises a first plurality of nanowires disposed along at least a first direction and the second layer comprises a second plurality of nanowires disposed along at least a second direction that is not parallel to the first direction, and wherein the first and second plurality of nanowires are configured to couple in the base configuration to form a wire-nanowire network having infrared reflectance and absorbance characteristics that are different from reflectance and absorbance characteristics of the first and second plurality of nanowires in a spaced-apart configuration.

18. The adaptive sheet of claim 14, wherein the first and second materials define a portion of a braid.

19. The adaptive sheet of claim 14, wherein the first and second materials define a portion of a knit.

20. The adaptive sheet of claim 14, wherein the lofted configuration responsive to the second environmental condition comprises a thickness of the adaptive sheet that is at least 1 mm greater than a thickness of the adaptive sheet of the base configuration responsive to the first environmental condition.